This invention relates to friction clutches, and more specifically to a cooling system for such clutches.
It is well known to use so-called wet friction clutches for heavy duty applications in vehicles. When the duty cycle of the clutch includes, for example, a high frequency of clutch engagements, or heavy loads upon vehicle start, or both, substantial heat is generated due to the relative rotation under load between the driving and driven members of the clutch. This heat is dissipated by passing a cooling liquid, usually oil, between the interleaved driving and driven members of the clutch.
The periods of heat generation in a friction clutch basically occur when the clutch is in a partially disengaged condition (the driving members are rotating and the driven members are stationary) or during clutch engagement (both driving and driven members are rotating, but at different speeds). Because the driven elements of the clutch are rotating not at all or relatively slowly during both periods of heat generation, the cooling liquid supplied to the center of the clutch is distributed mainly over only the lower portions of the friction members in wet cluches which rely in large part upon centrifugal force imparted to the cooling liquid by the driven friction members to distribute cooling liquid to areas of heat build up, as exemplified by U.S. Pat. No. 3,749,217 entitled Fluid Clutch with Self-Contained Pump issued in the name of Carl D. Bush et al.
Our improved cooling system overcomes the problem described above by utilizing the rotation of the driving members of the clutch to impart movement to the cooling liquid to propel it into the upper portions of the clutch. Since the driving members of the clutch are rotating when the clutch is disengaged and rotating at a high speed relative to the driven members during clutch engagement, cooling liquid will be supplied uniformly completely around the driving and driven members with the result that heat build up in the upper portions of the driving and driven members is substantially reduced, resulting in improved clutch life and operation.